I have 98 1500 5.7 and i have code for speed senser truck acted like was out of gas have checked fuel its good and checked spark its good could problem be speed senser, will not start now

Make sure battery has a full charge. If it cranks good but won't start, have a helper crank it while you check for spark at the plugs. If spark everywhere, use a gage and check proper fuel pressure and fuel injector pulse. Can you check for applicable trouble codes?
Unless you can do some testing, I don't know how to help?

Check for trouble codes. Battery good? Doe engine crank over at normal speed?
Gas, air, spark, and compression: what the cylinders need to fire. No starts are usually gas or spark related. So check for spark at a spark plug wire end to see if ignition related problem, and check fuel pressure for a gas problem. Do you hear the fuel pump turn on for a couple of seconds when you turn the key to on?

check the engine coolant temp sensor. Computer uses that to determine how much gas to feed on a cold start

why were the sensors replaced? what symptoms do you have, does it have a long cranking time before it runs?

I will try to add a few things to check. It sounds like bad plug wires or a coil going out. Sometimes if you water mist the coil and wires with a spray bottle you can see the sparks jump. It will be easier to see in a dark area with the motor running.

The Intake manifolds were changed from metal to plastic to prevent carbon buildup in the EGR passage. This would be under the Metal Airhorn and under the gasket where it attaches to the top of the Intake. There is a groove to clean that carbons up and throws bad codes and interferes with the engine running good. 8 bolts and a $10 gasket and 1Hour of your time to fix it.

You have not mentioned any codes or testing results. Your onboard computer can be checked for free at Autozone or Oreillys. Your "check engine" light should start setting defect codes if your misfires are getting worse. Also, if you can remember a wet plug when you removed your old plugs, that would be a good indicator of a bad wire for that cylinder.

Let me know if you have been fixed.

This code refers to fuel system malfunction. Fuel trim can go beylond the limits of the computers to tune the car for alot of reasons. the most common reasons that will go away are (1) you changed to differnt gas and the computer couldn't adapt to it fast enough and it turned the light on ( theirs nothing wrong with your car) try to run your car on the same fuel to avoid this problem and this is true with all cars and trucks even older ones. (2) any kind of tuneup problem, ( not changing the oil, Air filter, Antifreeze, on a timly basic) (3) A senser failed ( you noticed that this is third) Cars don't fail as much as thier owners adbuse them ( forget to do basic servives on time) The primary oxagen senser reports this problem to the computer but it only fails if the car has lots of miles, or the wrong fuel is run in it. Mazda sensers are very good and therefore they cost alot to change and the computer is so sensitive that an aftermarkey( parts store ) senser may cause more harm than good. If you don't have a true scanner, ( not a code reader ) then you need to hire this senser dianosic done so you don't change unnessary parts. ( example lets stay it has a bad plug wire and one cyclinder misses just enough to send enough raw gas down the exhuast to make the mixture off. You go changing the oxagen senser and foul the new one with the raw unburnt gas and when you do get it fixed correctly you have to change the senser and get the correct repair also. A bad map senser can do this too even a vacume leak in any hose or evewn a break problem that makes the power break booster use too much vacume. And the list of things that will change the mixture go on and on. Get the code reset and keep an eye on how it runs and how much gas it's useing. the light comes back on tell your scanner operator as much as you can about how it's been running (even real good, and even good gas mileage) your mechanic does'nt what to break a good thing.

first thing i would do is compresion test if good go thru fuses and relay check all grounds

Do you have fuel pressure. Put a gauge on it
(Fuel filter,fuel pump)
The vehicle isn't moving,so forget the speed sensor for now,depending on which one it is. (PO722 is output sensor)
When it quits,what are you losing. Air,Spark or Fuel,data?

need to have a fuel pressure test also make sure egr is not open at idle car wont run with egr open at idle

This is caused by some sort of fuel restriction within the fuel filter or, it could be a weak or failing pump as well.

I recommend changing the fuel filter and replacing the fuel pump. You can also benefit from replacing the spark plugs and wires. this will improve the performance of this vehicle.

If the engine light is illuminated, it is best to get the codes by running a diagnostic scan soon on the ecm.